Drop on demand ink jet technology is widely used in the printing industry. Printers using drop on demand ink jet technology can use either thermal ink jet technology or piezoelectric technology. Even though they are more expensive to manufacture than thermal ink jets, piezoelectric ink jets are generally favored as they can use a wider variety of inks and eliminate problems with kogation.
Piezoelectric ink jet printheads typically include a flexible diaphragm and an array of piezoelectric elements (transducers) attached to the diaphragm. When a voltage is applied to a piezoelectric element, typically through electrical connection with an electrode electrically coupled to a voltage source using, for example, a flexible printed circuit (i.e., a flex circuit), the piezoelectric element bends or deflects, causing the diaphragm to flex which expels a quantity of ink from a chamber through a nozzle. The flexing further draws ink into the chamber from a main ink reservoir through an opening to replace the expelled ink.
One method for attaching a flex circuit to an array of piezoelectric elements is to emboss electrical contacts of the flex circuit and to use the flex circuit in conjunction with a patterned standoff adhesive, where openings in the standoff adhesive expose the top of each piezoelectric element. The embossed metal contacts of the flex circuit then make electrical contact with each element of the piezoelectric array.
As resolution and density of printheads increase, the area available to provide electrical interconnects decreases. Routing of other functions within the head, such as ink feed structures, compete for this reduced space and place restrictions on the types of materials used. Methods and structures for manufacturing a flex circuit that has a better form for connection to a piezoelectric element array would be desirable.